Method for producing a metal melt and corresponding multifunction lance

ABSTRACT

The invention relates to a method for producing a metal melt in a metallurgical vessel, in particular an iron or steel melt, feed substances which contain metals and/or metal oxides, being charged in solid and, if appropriate, molten form into the metallurgical vessel, the main part of the energy necessary for the melting and, if appropriate, finish-reduction of the feed substances being applied electrically and/or by the combustion and/or gasification of carbon-containing materials. The invention relates, further, to multi-functional lances for use in a method according to the invention.

The invention relates to a method for producing a metal melt in ametallurgical vessel, in particular an iron or steel melt, feedsubstances, which contain metals and/or metal oxides, being charged insolid and, if appropriate, molten form into the metallurgical vessel,the main part of the energy necessary for the melting and, ifappropriate, finish-reduction of the feed substances being appliedelectrically and/or by the combustion and/or gasification ofcarbon-containing materials. The invention relates, further, to amulti-functional lance for use in a method according to the invention.

EP 0 257 450 A2 teaches a method for increased energy introduction andcurrent saving in arc furnaces for steelmaking. In this case, freeoxygen jets emanating from blow-on devices are used for thepost-combustion of the furnace waste gases and under-bath nozzles areused for moving the bath. Coal for the formation of CO is blown in via ahollow electrode or under-bath nozzles and the oxygen for the formationof CO is likewise supplied to the melt through under-bath nozzles.

A disadvantage, here, is the high outlay in terms of apparatus forblowing in the coal, the formation of CO and post-combustion.Furthermore, the under-bath nozzles required, which are loaded withoxygen, are exposed to high wear and, correspondingly, have only a shortservice life.

There have also been many attempts to make devices and methods availablefor heating and blowing for metallurgical purposes and for combustion inmetallurgical reactors.

Thus GB 1,015,581 discloses a burner with a central oxygen duct, with afuel supply duct surrounding the latter and with an outer annular ductfor oxygen. The fuel and oxygen are intermixed immediately afteremerging from the respective mouths. According to GB 1,015,581, theburner is provided for use in all top-blowing oxygen steelmakingmethods.

However, such a burner is unsuitable for sucking in furnace gases to anappreciable extent for post-combustion, so that it can contributenothing or only little to improving the energy balance.

AT 402,963 B describes the combustion of fuel by means of a speciallydesigned burner. As a result of the rapid intensive swirling of the fueltogether with oxygen in a chamber of the burner, the outflowing mixturevery soon becomes relatively slow over the running distance of themixture jet. Such a burner therefore has relatively short flame lengthand in this case, once again, neglects to suck in furnace gases, so thatthis, too, can contribute little to improving the energy balance.Furthermore, such a burner is suitable only to a limited extent for therefining of a steel melt.

WO 91/00366 describes a method and a device for heating a metallurgicalfurnace, an inner oxygen duct being encased annularly by a fuel duct. Inthis case, the fuel is supplied by means of an inert to weakly reducingcarrier gas. Here too, no possibility is given for the post-combustionof furnace waste gases by sucking them into the burner jet or for therefining of the melt.

The object of the present invention is, therefore, to provide a methodand a device for use in such a method which avoid the disadvantagesknown from the prior art. In particular, a method is to be provided,which requires less energy, both electric and fossil, than known methodsin order to produce a metal melt and which can be carried out in ashorter time, and multi-functional lances are to be provided, by meansof which the method according to the invention can be carried out andwhich, furthermore, are kept compact and simple in terms of constructionand, when a repair is necessary, can be repaired again easily andsimply.

This object is achieved, according to the invention, by means of thecombination of the following features:

that

A) in a combustion step, additional energy is supplied to the feedsubstances by the blowing-in, taking place by means of one or moremulti-functional lances, and combustion of gaseous and/or liquidcarbon-containing materials and oxygen-containing gas,

B) in a cutting and melting step, the solid feed substances are cut andpartially melted by the intensified blowing-in, taking place by means ofthe multi-functional lance or lances, of oxygen-containing gas,

C) in a refining step, the melted feed substances are refined by theintensified blowing-in, taking place by means of the multi-functionallance or lances, of oxygen-containing gas,

D) in a carbon blow-in step, alloying carbon and/or additional energy issupplied to the feed substances by the blowing-in, taking place by meansof the multi-functional lance or lances, and, if appropriate, combustionof fine-grained and/or dust-like solid carbon-containing materials,

E) in a post-combustion step, the waste gases from the metallurgicalvessel are afterburnt by the blowing-in, taking place by means of themulti-functional lance or lances and directed away from the respectivemulti-functional lance in at least two of the three spatial directions,of oxygen-containing gas into the waste-gas space of the metallurgicalvessel,

F) in a solid blow-in step, the necessary substances are supplied to thefeed substances by the blowing-in, taking place by means of themulti-functional lance or lances, of fine-grained and/or dust-like solidaggregates and/or alloying agents, in order to achieve the desiredcomposition of the metal melt,

steps A) to F) being carried out, depending on the composition of thefeed substances and on the desired composition of the metal melt,selectively in any desired combination, in particular in successionand/or in reverse order and/or simultaneously and/or omitting individualsteps of steps A) to F).

By means of the method according to the invention, metal melts can,according to an advantageous feature, be produced, for example, inelectric furnaces or converters or melt-down gasifiers or in aparticularly energy-saving and time-saving way. Furthermore, ladles orvessels for the conversion of slag may be used as metallurgical vessels.The respective metallurgical vessel may be under overpressure,atmospheric pressure, underpressure or a vacuum.

The multi-functional lances used for the method according to theinvention make it possible to carry out the individual method stepsflexibly, with free choice and, in particular, also simultaneously.

There is an increase in the use of solid metal carriers for producingmelts, in particular steel melts, since these materials are alreadymetallic and therefore no longer have to be reduced at a high outlay.Such solid metal carriers are therefore recirculated to an increasingextent. In particular, such materials, such as scrap, pig iron, castiron, etc., are processed in electric furnaces, so that it isparticularly important to improve the operation of electric furnaces.Rapid melting-down and refining in order to set short furnace cycletimes are important for achieving low heat losses and electrodeconsumptions and for the uninterrupted feeding of modern continuouscasting plants. Moreover, the melting capacity of electric furnaces isalso to be increased as a result of the controlled parallel introductionof electric and fossil energy.

These requirements are satisfied by the method according to theinvention.

According to an advantageous feature of the method according to theinvention, one or more multi-functional lances are used jointly withburners and/or refining lances and/or post-combustion lances and/or, inthe case of electric furnaces, under-bath nozzles and/or hollowelectrodes and/or, in the case of converters, side nozzles, which ineach case are known per se.

It is thereby possible that burners and/or refining lances and/orpost-combustion lances cover, as it were, the basic loads of acorresponding method step and, in addition, energy is introduced,melting carried out, refining carried out, coal and/or alloying agentblown in, waste gas afterburnt, etc., at particularly important pointsby means of the multi-functional lance or lances additionally used, forthe purpose of achieving a rapid method flow.

In a further advantageous embodiment of the method according to theinvention, in a solid blow-in step, one or more of the followingsubstances is or are blown into or onto the partially or completelymelted feed substances: metal ores, such as chrome ore, nickel ore andmanganese ore, metal oxides, such as nickel oxide, vanadium oxide andchrome oxide, iron carbide, calcium carbide, aluminium, FeSi, FeCr,FeMn, oil-containing scale, slags, slag formers, dusts from dedustingsystems, grinding dusts, metal chips, deoxidants, shredderlightfraction, lime, coal, coke and sponge iron, in each case in fine-grainedand/or dust-like form.

If a plurality of substances are to be blown in, these may be blown,intermixed or separately, into/onto the partially or completely meltedfeed substances. The introduction of a mixture of substances may, forexample, then be somewhat advantageous when metal ores and/or metaloxides are blown in jointly with deoxidants.

Preferably, in a post-combustion step, the blowing-in ofoxygen-containing gas takes place in a periodically fluctuating and/orpulsating manner.

As a result, the post-combustion of the waste gases from themetallurgical vessel can be carried out particularly efficiently, sothat the energy released at the same time is transmitted with highefficiency to the feed substances and is not lost to the waste-gassystem which is even relieved of thermal load.

According to a further embodiment of the method according to theinvention, in a carbon blow-in step and/or a solid blow-in step in anelectric furnace, the jet from a multi-functional lance is directed intothe vicinity of the point of impingement or into the point ofimpingement of solid material, which is charged onto the melt via anorifice in the furnace roof, or of an arc on the melt.

According to an equally advantageous embodiment, in a carbon blow-instep and/or a solid blow-in step in a converter, the jet from amulti-functional lance is directed into the vicinity of the point ofimpingement or into the point of impingement of an oxygen jet from afurther lance or a side nozzle on the melt.

The two last-mentioned embodiments are advantageous particularly whenlarge quantities of ores, NiO, oxidic fines and dusts, which in eachcase may also be mixed with coal, have to be reduced. The reduction andmelting of the feed substances are particularly accelerated by theintroduction of carbon at the point or points where the greatest supplyof energy also simultaneously takes place.

According to a particularly advantageous feature of the method accordingto the invention, one or more of the method steps A, B, D, E and F arecarried out by means of a multi-functional lance essentiallysimultaneously with a refining step, particular preference being givento carrying out a combustion step essentially simultaneously with arefining step. By “essentially simultaneously” is meant, here, an atleast partial time overlap of the two method steps.

In addition to the intensified blowing-in of oxygen-containing gas, as aresult of which the melted feed substances are refined, liquid and/orgaseous carbon-containing substances and oxygen-containing gas are alsoblown in and the carbon-containing substances are burnt.

According to a further advantageous feature of the method according tothe invention, in a refining step during the production of preferablyalloyed iron melts with a low carbon content, steam and/or an inert gas,such as nitrogen, and/or rare gases are blown into or onto the partiallyor already completely melted feed substances, in addition to theintensified blowing-in of oxygen-containing gas.

Consequently, the CO partial pressure and therefore iron slagging, aswell as the slagging of alloying elements, in particular, chromeslagging, are reduced appreciably.

According to one embodiment of the method according to the invention, ina carbon blow-in step for the production of iron melts or steel meltswith a low carbon content, the carbon-containing materials are blown atlow velocity only onto and into the slag located above the melt.

Additional refining of the melt is thereby avoided here. Thecarbon-containing materials then serve primarily for the foaming of theslag.

As a result of a further advantageous embodiment of the method accordingto the invention, a liquid blow-in step (G) is carried out during one ormore of the method steps A, B, C, and E, burnable and/or unburnable,possibly toxic liquids which are otherwise difficult to dispose of, forexample halogenated carbons or oils, being blown in by means of themulti-functional lance or lances, thermally decomposed and therebydisposed of in an environmentally friendly manner.

By liquids are also meant, in this respect, solutions of disposablesolids in corresponding solvents.

Preferably, the liquid blow-in step takes place onto the hottest pointin the metallurgical vessel, and, consequently, it is particularlypreferred to carry out the liquid blow-in step during a refining step orto direct the liquid jet onto the point of impingement of an arc on themelt.

In conjunction with an appropriate aftertreatment of the waste gas fromthe metallurgical vessel, such as, for example, quenching, theblowing-in of activated charcoal, etc., it is possible for liquids whichare difficult to dispose of to be disposed of not only in anenvironmentally compatible way, but also profitably.

According to a further embodiment of the method according to theinvention, during a refining step (C) the blown-in jet of theoxygen-containing gas is influenced in a controlled manner by theblowing-in, taking place by means of the multi-functional lance, of afurther gas jet.

The subject of the invention is also a multi-functional lance for use inthe method according to the invention, having a plurality of tubes whichsurround one another and are concentric to a central longitudinal axisand a common end of which forms the head of the multi-functional lance.

The solution for achieving the object set according to the inventiondepends, inter alia, on whether the multi-functional lance is to besuitable for blowing in large or small solid quantities.

For blowing in small solid quantities, the object set according to theinvention is achieved by means of the combination of the followingfeatures:

a first tube (1) for forming a supply duct, in particular for solid,fine-grained to dust-like substances,

a second tube (3) surrounding the first tube (1) so as to form a firstannular gap (4), in particular for the supply of an oxygen-containinggas, the mouth part (6) of the second tube (3) being designed as a Lavalnozzle,

a third tube (7) surrounding the second tube (3) so as to form a secondannular gap (8), in particular for the supply of gaseous and/or liquidfuel,

a fourth tube (9) surrounding the third tube (7) so as to form a thirdannular gap (10), in particular for the supply of an oxygen-containinggas,

a fifth tube (11) surrounding the fourth tube (9) so as to form a fourthannular gap (12), in particular for the supply of an oxygen-containinggas, the fourth annular gap (12) terminating, on the mouth side, so asto form a plurality of outflow ducts (13), and the direction of flowbeing directed through each outflow duct (13) away from the centrallongitudinal axis (2).

Particularly advantageous, here, is the first tube, through whichpredominantly fine-grained and/or dust-like solids are blown into and/oronto the melt or slag. Depending on the method step, in a carbon blow-instep, a supply of carbon-containing materials, in particular coal, but,for example, also coke and/or shredderlight fraction, is carried out,and, in a solid blow-in step, a supply of aggregates and/or alloyingagents is carried out, by aggregates and alloying agents being meant allconventional slag formers, slag-foaming agents, agents for the oxidationof undesirable accompanying elements, agent for setting the desiredcomposition of the metal melt, etc., which are normally used in theproduction of metal melts, in particular of steel and pig-iron melts.The first tube makes it possible for the multi-functional lanceaccording to the invention to perform the carbon and solid blow-infunctions.

Solids of an order of magnitude of up to 10 kg/min can be blown in bymeans of the multi-functional lance characterized by the above featurecombination.

Since the mouth part of the second tube is designed as a Laval nozzle,the admission pressure of the oxygen-containing gas supplied duringcutting and melting steps and during refining steps can be convertedinto a pulse, that is to say velocity. The first annular gap formed bythe first and second tubes makes it possible for the multi-functionallance according to the invention to perform the cutting, melting andrefining functions.

By oxygen-containing gas is preferably meant industrial oxygen, such asis obtained, for example, from an air separation plant, or air or airenriched with oxygen.

The second and third annular gaps serve, in a combustion step, for thesupply of gaseous and/or liquid fuel, for example natural gas and/orfuel oil, or for the supply of oxygen-containing gas, in particularindustrial oxygen, by means of which the fuel is burnt. The second andthird annular gaps together make it possible for the multi-functionallance according to the invention to perform the burner function for acombustion step.

The fourth annular gap formed by the fourth and fifth tubes serves, in apost-combustion step, for the supply of oxygen-containing gas and thusmakes it possible for the multi-functional lance according to theinvention to perform the post-combustion function.

According to a preferred embodiment, the fourth annular gap terminates,on the mouth side, so as to form 2 to 16, preferably 4 to 6 outflowducts.

The outflow ducts are directed away from the central longitudinal axispreferably in such a way that the normal projection of the centre axisof each outflow duct onto a plane drawn through the central longitudinalaxis and through the mouth of the outflow duct forms with the centrallongitudinal axis an angle α of 2.5 to 25°, preferably an angle α of 5to 15°.

By virtue of this design of the outflow ducts, by means of theoxygen-containing gas, which is fed to the atmosphere of themetallurgical vessel through the outflow ducts, a wide region of thisatmosphere can be covered and burnable waste gases can be afterburnt.

According to an advantageous feature, the centre axes of the outflowducts are skew to the central longitudinal axis of the multi-functionallance, specifically in such a way that the normal projection of thecentre axis of each outflow duct onto a plane directed normally to thecentral longitudinal axis forms, with a plane drawn through the centrallongitudinal axis and through the mouth of the outflow duct, an angle βof 2.5 to 60°, preferably an angle β of 5 to 200.

This design of the outflow ducts allows an even more comprehensivepost-combustion of waste gases from the metallurgical vessel, since, asa result, the oxygen-containing gas blown in via the outflow ducts and,consequently, also the waste gases from the metallurgical vessel, whichare sucked into these oxygen gas jets, are set in helical rotationalmovement. This assists the intermixing of the oxygen-containing gas withthe waste gases and the post-combustion of these.

The individual angles α and β may also be selected differently in eachcase for individual outflow ducts, in order to take optimally intoaccount special boundary conditions when the multi-functional lance isused.

The outermost, that is to say fifth tube is advantageously provided withcooling which is preferably designed as a water-cooled double casing.

By means of the cooling provided according to this feature, the lifetimeof the multi-functional lance is prolonged.

According to a further advantageous feature, the mouth parts of thesecond and/or of the third tube have slots on the outside, these slotspreferably being arranged parallel to the central longitudinal axis.These slots serve for the improved cooling of the respective mouth part.

According to an advantageous design variant, the mouth parts of thefirst, of the second and of the third tube terminate in a first mouthplane normal to the central longitudinal axis and the mouth parts of thefourth and fifth tubes terminate in a second mouth plane normal to thecentral longitudinal axis, the first mouth plane being set back behindthe second.

In this case, the water-cooled double casing is also expediently drawnforwards as far as the second mouth plane.

The tubes arranged inside the multi-functional lance are thereby betterprotected against mechanical stress at their mouth.

So that repair work can be carried out quickly and simply, the mouth endof the second tube is formed by a mouth part releasably connected, inparticular screwably connected, to the second tube.

According to advantageous embodiments, the first and, if appropriate,the second tube are designed to be wear-resistant.

The wear-resistant design of the first and, if appropriate, the secondtube is preferably such that the first and, if appropriate, the secondtube are manufactured from an alloyed steel with chromium carbides orfrom a hard-chrome-plated steel or from hard-chrome-plated copper orfrom copper or a steel which is provided with a ceramic insert orcovering on the inside and, if appropriate, on the outside.

These wear-resistant designs make it possible to blow abrasive media,such as, for example, fine-grained coal, metal oxides, slag formers andthe like, through the first tube and, if appropriate, through theannular gap formed by the first and second tubes into or onto the meltor slag by means of a carrier gas, without thereby appreciablyshortening the lifetimes of the first and second tubes.

So that, furthermore, repairs can be carried out particularly quicklyand simply, advantageously the third and fourth tubes are divided intheir length and the respective tube parts are fastened to one anotherby means of releasable connections, in particular screw connections.

According to a further advantageous embodiment, in addition to the mouthof the second tube, the mouth or mouths of the first and/or the thirdand/or the fourth tube and/or the outflow ducts are also designed asLaval nozzles.

This is expedient, in particular, in order, in addition to the refiningand cutting function, also to obtain a high velocity and, consequently,pulse and range or depth of penetration of the respective gas and/orgas/solid jets for one or more of the functions, namely burner, carbonand solid blow-in and post-combustion.

The Laval nozzle form of the mouth of the second tube is expedientlydesigned in such a way that the aperture angle γ of the conical part ofthe mouth of the second tube is 0.1 to 5°, preferably 0.5 to 3°.

The choice of the aperture angle γ also depends, inter alia, on theconditions prevailing in the melting vessel. Thus, if the melting vesselis under overpressure, somewhat lower values are selected for γ,whereas, in the case of a melting vessel in which underpressure or avacuum prevails, higher values are advantageous.

As a result of a further advantageous embodiment, the first tube can bemoved within the second tube along the central longitudinal axis, sothat further influence can be exerted on the solid and carbon blow-infunction. Furthermore, when the first tube is moved behind thecontraction of the second tube, an increase in the oxygen quantity to beblown, in the case of a given admission pressure, can consequently beachieved.

In order to supply the multi-functional lance with carrier gas, thefirst tube as well as the first, the second, the third and the fourthannular gap are in each case connected to a carrier-gas supply, inparticular an inert-gas supply.

Depending on the method step currently being carried out, carrier gas orinert gas can serve as injector gas for carbon or solid injection or forsetting a specific oxygen content of the oxygen-containing gas suppliedduring a cutting and melting, refining or combustion step. Furthermore,the multi-functional lance, before being used in the method according tothe invention, or the blowing cross sections not used at that particulartime, can be scavenged with a small stream of inert gas and kept free ofsplashes of metal.

In order to supply the multi-functional lance with all the other gasesnecessary for the method steps, the first tube as well as the first, thethird and the fourth annular gap are in each case connected to an oxygensupply, an air supply, if appropriate a steam supply and connectable anddisconnectable solid injection and the second annular gap is connectedto a fuel supply for the supply of liquid and/or gaseous fuel.

So that, if appropriate, oxygen can also be blown through the firsttube, which otherwise serves predominantly for blowing coal and solids,in a cutting and melting and/or refining step, a change-over from thecarrier-gas and solid supply of the first tube to the supply of oxygencan be made by means of a change-over device, in particular achange-over valve.

Advantageously, the supply of gases to the multi-functional lance can beregulated by setting the admission pressure of the respective gas.

Alternatively or additionally to this, the supply of gases to themulti-functional lance can be set by means of simple rigid diaphragmsand/or quick-acting stop valves which in each case are arranged in theindividual gas lines.

The object set according to the invention is achieved, furthermore, forthe blowing-in of large solid quantities, by means of the combination ofthe following features:

a first tube for forming a supply duct, in particular for liquids oroxygen-containing gas,

a second tube surrounding the first tube so as to form a first annulargap, in particular for the supply of an oxygen-containing gas, the mouthpart of the second tube being designed as a Laval nozzle,

a third tube surrounding the second tube so as to form a second annulargap, in particular for the supply of gaseous and/or liquid fuel,

a fourth tube surrounding the third tube so as to form a third annulargap, in particular for the supply of an oxygen-containing gas,

a fifth tube surrounding the fourth tube so as to form a fourth annulargap, in particular for the supply of cooling water, the fourth annulargap being designed to be closed on the mouth side,

a sixth tube surrounding the fifth tube so as to form a fifth annulargap, in particular for the supply of oxygen-containing gas, the fifthannular gap terminating, on the mouth side, so as to form a plurality ofoutflow ducts, and the direction of flow being directed through eachoutflow duct away from the central longitudinal axis,

a seventh tube surrounding the sixth tube so as to form a sixth annulargap, in particular for drawing off cooling water, the sixth annular gapbeing designed to be closed on the mouth side, and the fourth annulargap being connected to the sixth annular gap, in the region of the headof the multi-functional lance, by means of bores which do not cross theoutflow ducts,

one to nine nozzle tubes of wear-resistant design, in particular for thesupply of solid, fine-grained to dust-like substances, the nozzle tubesbeing arranged within the fifth annular gap and the centre axis of eachnozzle tube being arranged parallel to the longitudinal axis, and thenozzle tubes piercing the head of the multi-functional lance, withoutcrossing bores or outflow ducts.

Particularly advantageous, here, are the nozzle tubes, through whichfine-grained and/or dust-like solids are blown into and/or onto the meltor slag. Depending on the method step, in a carbon blow-in step, asupply of carbon-containing materials, in particular coal, but, forexample, also coke and/or shredderlight fraction, is carried out, and,in a solid blow-in step, a supply of aggregates and/or alloying agentsis carried out, by aggregates and alloying agents being meant allconventional slag formers, slag-foaming agent, agent for the oxidizationof undesirable accompanying elements, agent for setting the desiredcomposition of the metal melt, etc., which are normally used in theproduction of metal melts, in particular of steel and pig-iron melts.The nozzle tubes make it possible for the multi-functional lanceaccording to the invention to perform the carbon and solid blow-infunctions.

The multi-functional lance characterized by the above featurecombination is pre-eminently suitable for also blowing in very largesolid quantities of up to 200 kg/min. This is particularly advantageouswhen relatively large fractions of electrical energy, which werehitherto necessary for producing the melt, are to be replaced by fossilenergy, in order, for example, to increase productivity further or whenrelatively large quantities of the abovementioned solids are to be blownpneumatically into the slag and/or melt for a wide variety of instancesof use.

Since the mouth part of the second tube is designed as a Laval nozzle,the admission pressure of the oxygen-containing gas supplied duringcutting and melting steps and during refining steps can be convertedinto a pulse, that is to say velocity. The first annular gap formed bythe first and second tubes makes it possible for the multi-functionallance according to the invention to perform the cutting, melting andrefining functions.

By oxygen-containing gas is preferably meant industrial oxygen, such asis obtained, for example from an air separation plant, or air or airenriched with oxygen.

The first tube serves for the reproducible control of the pulse of theLaval jet out of the first annular gap, in that the jet propagation and,consequently, also the refining effect of the Laval jet are regulated bymeans of the first tube. This is also employed in order not to subjectthe refractory bottom of the metallurgical vessel to additional wear inthe case of a low bath height or in order to ensure, in a controlledmanner, higher FeO contents in slags above steel melts, so as thereby toimprove appreciably the dephosphorization of the metal melts, even whenthe carbon contents of the melt are relatively high. Themulti-functional lance according to the invention therefore also has thecapability of controlling the iron oxide contents of the slags and,consequently, the dephosphorization, but, for example, also thedevanadization, of the iron melt.

Liquids to be disposed of can also be injected through the first tubeinto the Laval jet or the focal spot in front of the multi-functionallance. The first tube thus makes it possible, inter alia, for themulti-functional lance according to the invention to perform the liquidblow-in function.

Normally, however, the first tube is loaded with oxygen oroxygen-containing gas. During the refining of alloyed melts, the firsttube can be loaded with air or inert gas or steam, in order to lower theCO partial pressure at the focal spot in front of the multi-functionallance and, consequently, reduce chromium slagging.

In a combustion step, the second and third annular gaps serve for thesupply of gaseous and/or liquid fuel, for example natural gas and/orfuel oil, or for the supply of oxygen-containing gas, in particularindustrial oxygen, by means of which the fuel is burnt. The second andthird annular gaps together make it possible for the multi-functionallance according to the invention to perform the burner function for acombustion step.

The fifth annular gap formed by the fifth and sixth tubes serves, in apost-combustion step, for the supply of oxygen-containing gas and thusmakes it possible for the multi-functional lance according to theinvention to perform the post-combustion function.

The lifetime of the multi-functional lance is prolonged by means of thecooling casing formed by the fourth and sixth annular gaps and by thebores connecting these annular gaps and located in the head of themulti-functional lance.

According to a preferred embodiment, the fifth annular gap terminates,on the mouth side, so as to form 2 to 16, preferably 4 outflow ducts.

The outflow ducts are directed away from the central longitudinal axispreferably in such a way that the normal projection of the centre axisof each outflow duct onto a plane drawn through the central longitudinalaxis and through the mouth of the outflow duct forms with the centrallongitudinal axis an angle α of 2.5 to 25°, preferably an angle α of 5to 15°.

By virtue of this design of the outflow ducts, by means of theoxygen-containing gas, which is fed to the atmosphere of themetallurgical vessel through the outflow ducts, a wide region of thisatmosphere can be covered and burnable waste gases can be afterburnt.

According to an advantageous feature, the centre axes of the outflowducts are skew to the central longitudinal axis of the multi-functionallance, specifically in such a way that the normal projection of thecentre axis of each outflow duct onto a plane directed normally to thecentral longitudinal axis forms, with a plane drawn through the centrallongitudinal axis and through the mouth of the outflow duct, an angle βof 2.5 to 60°, preferably an angle β of 5 to 20°.

This design of the outflow ducts allows an even more comprehensivepost-combustion of waste gases from the metallurgical vessel, since, asa result, the oxygen-containing gas blown in via the outflow ducts and,consequently, also the waste gases from the metallurgical vessel, whichare sucked into these oxygen gas jets, are set in a helical rotationalmovement. This assists the intermixing of the oxygen-containing gas withthe waste gases and the post-combustion of these.

The individual angles α and β may also be selected differently in eachcase for individual outflow ducts, in order to take optimally intoaccount special boundary conditions when the multi-functional lance isused.

The Laval nozzle form of the mouth of the second tube is expedientlydesigned in such a way that the aperture angle γ of the conical part ofthe mouth of the second tube is 0.1 to 5°, preferably 0.5 to 3°.

The choice of the aperture angle y also depends, inter alia, on theconditions prevailing in the melting vessel. Thus, if the melting vesselis under overpressure, somewhat lower values are selected for γ,whereas, in the case of a melting vessel in which underpressure or avacuum prevails, higher values are advantageous.

According to a further advantageous feature, the mouth parts of thesecond and/or of the third tube have slots on the outside, these slotspreferably being arranged parallel to the central longitudinal axis.These slots serve for the improved cooling of the respective mouth part.

According to an advantageous design variant, the mouth parts of thesecond and of the third tube terminate in a first mouth plane normal tothe central longitudinal axis and the mouth parts of the fourth, fifth,sixth and seventh tube terminate in a second mouth plane normal to thecentral longitudinal axis, the first mouth plane being set back behindthe second.

The tubes arranged inside the multi-functional lance are thereby betterprotected against mechanical stress at their mouth.

As a result of a further advantageous embodiment, the first tube can bemoved within the second tube along the central longitudinal axis, sothat further influence can be exerted on the Laval jet from the firstannular gap. Furthermore, when the first tube is moved behind thecontraction of the second tube, an increase in the oxygen quantity to beblown, in the case of a given admission pressure, can consequently beachieved.

So that repairs can be carried out quickly and simply, the mouth end ofthe second tube is formed by a mouth part releasably connected to thesecond tube, in particular connected to it screwably or by means of asliding connection sealed off by means of O-rings.

So that, furthermore, repairs can be carried out particularly quicklyand simply, advantageously the third and/or the fourth and/or the fifthand/or the sixth and/or the seventh tube are divided at least once intheir length and the respective tube parts are fastened to one anotherby means of releasable connections, in particular screw connectionsand/or sliding connections sealed off by means of O-rings.

According to a further advantageous embodiment, in addition to the mouthof the second tube, the mouth or mouths of the third and/or of thefourth tube and/or the outflow ducts and/or the mouth or mouths of thenozzle tube or nozzle tubes are also designed as Laval nozzles and/orthe mouth of the first tube is widened in diameter.

This Laval nozzle form is expedient, in particular, in order, inaddition to the refining and cutting function, also to obtain a highvelocity and, consequently, pulse and range or depth of penetration ofthe respective gas and/or gas/solid jets for one or more of thefunctions, namely burner, carbon and solid blow-in and post-combustion.

The widening of the mouth diameter of the first tube is advantageous, inparticular, in the case of a melting vessel which is under underpressureor a vacuum.

According to an advantageous embodiment, the nozzle tube or nozzle tubesis or are designed to be wear-resistant.

The wear-resistant design of the nozzle tubes is preferably such thatthe respective tube is manufactured from an alloyed steel with chromiumcarbides or from a hard-chrome-plated steel or from hard-chrome-platedcopper or from copper or a steel which is provided with a ceramic insertor covering on the inside and, if appropriate, on the outside.

These wear-resistant designs make it possible to blow abrasive media,such as, for example, fine-grained coal, metal oxides, slag formers andthe like, through the nozzle tubes into or onto the melt or slag bymeans of a carrier gas, without thereby appreciably shortening thelifetimes of the nozzle tubes.

In a further advantageous embodiment of the multi-functional lanceaccording to the invention, a solid-distribution chamber is assigned tothe nozzle tube or nozzle tubes at that end which faces away from thehead of the multi-functional lance, the solid-distribution chamber beingformed by an annular, essentially cylindrical hollow body enclosedall-round and having a bottom, a cover and a lateral limitation, and thenozzle tube or nozzle tubes piercing the bottom of thesolid-distribution chamber from below, and at least one solid supplyopening tangentially into the lateral limitation of thesolid-distribution chamber.

In addition to the above embodiment, a further annular, essentiallycylindrical hollow body is preferably provided, the further hollow bodybeing open at the top and having a bottom and a lateral limitation, andthe further hollow body being arranged within the solid-distributionchamber in such a way that a gap remains between the cover of thesolid-distribution chamber and the lateral limitation of the furtherhollow body, and the nozzle tube or nozzle tubes opening into the bottomof the further hollow body.

Solid is blown tangentially into the solid-distribution chamber and flows through the gap via an intermediate wall, formed by the laterallimitation of the further hollow body, into a space, from which thenozzle tubes lead away (that is to say, into the further hollow body).The entry to the nozzle tubes is conical and, like the nozzle tubesthemselves, is designed to be wear-resistant.

The solid-distribution chamber is fastened to the lance body by means ofa quick-acting fastening or a flange and, after the fastening has beenreleased, can be drawn off. The wear-resistant nozzle tubes are fastenedin a ring forming the bottom of the solid-distribution chamber and caneasily be exchanged.

The solid-distribution chamber of the multi-functional lance accordingto the invention is expediently connected to a carrier-gas supply, inparticular an inert-gas supply, and to one or more solid supplies.

Alternatively to this, that is to say when no solid-distribution chamberis provided, the nozzle tubes themselves are connected to a carrier-gassupply, in particular an inert-gas supply, and to one or more solidsupplies.

For the further supply of the multi-functional lance with carrier gas,the first tube as well as the first, the second, the third and the fifthannular gap are in each case connected to a carrier-gas supply, inparticular an inert-gas supply.

Depending on the method step currently being carried out, carrier gas orinert gas may serve as injector gas for carbon or solid injection or forsetting a specific oxygen content of the oxygen-containing gas suppliedduring a cutting and melting, refining or combustion step. Furthermore,the multi-functional lance, before being used in the method according tothe invention, or the blowing cross sections not used at that particulartime, can be scavenged with a small stream of inert gas or with air andbe kept free of splashes of metal.

In order to supply the multi-functional lance with all the other gasesnecessary for the method steps, the first tube as well as the first, thethird and the fifth annular gap are in each case connected to an oxygensupply, an air supply and, if appropriate, a steam supply, and thesecond annular gap is connected to a fuel supply for the supply ofliquid and/or gaseous fuel.

Additionally or alternatively to the supply of oxygen and/or air, thefirst and/or the fifth annular gap may be provided with a hot-blastsupply. By hot blast is to be meant, in this case, an oxygen-containinggas, for example air enriched with oxygen, at a temperature of 200 toabout 1200° C.

Advantageously, the supply of gases to the multi-functional lance can beregulated by setting the admission pressure of the respective gas.

Alternatively or additionally to this, the supply of gases to themulti-functional lance can be set by means of simple rigid diaphragmsand/or quick-acting stop valves which in each case are arranged in theindividual gas lines.

All the embodiments of the multi-functional lances according to theinvention have in common the fact that, as is known per se,electromagnetic waves, in particular in the range of visible light andof the adjacent infrared range, which are emitted by a metal melt, can,through the first tube and/or the first annular gap, be capable of beingdetected by means of an optical system and of being fed to a detectorfor determining the temperature and/or chemical composition of the metalmelt.

During such measurements, preferably inert gas is blown through thefirst tube and/or the first annular gap, and, at the same time, theburner function of the multi-functional lance can remain switched on. Inthis case, the evaluation of the electromagnetic waves for determiningthe temperature and/or chemical composition of the metal melt may becarried out by pyrometry and/or spectrometry. A similar method hasalready been proposed in WO 97/22859, the difference being that, here,measurement is not carried out under the bath, as in WO 97/22859.

The multi-functional lances according to the invention, in both theembodiment for smaller solid quantities and that for larger solidquantities, are advantageously arranged in such a way that they aredisplaceable and/or pivotable along their longitudinal axis.Consequently, on the one hand, the depth of penetration of therespective gas jets into the melt can be controlled and the runningdistance of the gas jets, in the case of a variable height of the bathsurface, can be set, and, on the other hand, a larger region of the bathsurface can be reached or swept.

It has proved advantageous, furthermore, to arrange a multi-functionallance below a copper panel bulged in the direction of the interior ofthe metallurgical vessel, the multi-functional lance remainingdisplaceable and/or pivotable, since it is thereby protectedparticularly well.

The number of multi-functional lances used in a metallurgical vessel forthe method according to the invention varies with the type ofmetallurgical vessel and its size and with the embodiments of themulti-functional lances used. One to 10 multi-functional lances may beprovided. The investment costs, which are higher in the case of largernumbers, are more than compensated by the fact that the introduction ofenergy, of carbon and of solids and the post-combustion take place in anessentially equalized manner over the entire furnace space or the entiremelt surface and the productivity of the respective metallurgical vesselis increased.

In the case of relatively large numbers of multi-functional lances, forexample 5, it is also advantageous for the multi-functional lances to bedesigned with smaller dimensions, so that the sum of the blowing crosssections is approximately the same as when a smaller number ofmulti-functional lances, for example only two multi-functional lances,are used.

The electric furnace and the converter are adopted hereafter as typical,but non-restrictive examples for describing the invention.

Unless specified otherwise, the following statements relate tomulti-functional lances for blowing in relatively large solidquantities.

In order to simplify the terminology, the first tube, the first, thesecond, the third and fifth annular gaps and the nozzle tubes, togetherwith the respectively associated mouth part and the outflow ducts, aredesignated hereafter as nozzle1, nozzle2, nozzle3, nozzle4, nozzle5 andnozzle6.

According to the invention, one or, in the case of larger furnaces, aplurality of multi-functional lances are arranged above the bathsurface, as measured before the tapping of the melt, preferably in theside wall, in the bay region or else so as to blast from the furnaceroof. The longitudinal axis of the multi-functional lance, if it isarranged in the side wall or in the bay region, is to have aninclination relative to the bath surface of more than 35°. Themulti-functional lance is, as a rule, arranged in a stationary manner.In the case of an arrangement in electric furnaces with long bricks inthe slag zone or sometimes also in the bay region of the electricfurnace, a linearly displaceable lance arrangement, with or without thepossibility of pivoting, is provided in the side wall and/or in the bayregion or in the furnace roof.

Depending on how the electric furnace is equipped with burners and/orpost-combustion lances corresponding to the prior art, themulti-functional lances are used preferably in the area of the colderfurnace regions (cold spots) or bay. In principle, however, themulti-functional lances may be used at all points on the furnacecircumference or so as to travel down from the furnace roof. In the caseof electric furnaces which are charged, for example continuously, withlarge quantities of sponge iron through a fifth roof hole, it isadvantageous to have an arrangement in which the jets from themulti-functional lances impinge in the vicinity of the point ofimpingement of the sponge iron on the melt, since energy is urgentlyrequired there, CO occurs and can be afterburnt and the formation of FeOis reduced by blowing in coal.

As regards the height of the lance position in the side wall, it must bestipulated that the running distance of, for example, the jet fromnozzle2 is to be less than 2 m, if the specific refining of the meltand, consequently, the penetration of the oxygen jet into the melt areimportant. In the bay of the electric furnace, the running distance ofthe jets is mostly below 1.2 m. In the converter or similar reactors,the running distances of the jets may even be substantially longer than2 m.

In order to optimize the electrode consumption, the multi-functionallances, when arranged in the side wall, are preferably arrangedtangentially to an imaginary cylinder. The cylinder diameter is betweenthe electrode reference circle and the furnace wall.

The multi-functional lance is preferably inserted into an intensivelycooled, approximately square copper panel having a side length of about0.5 m. The lifetime of the surroundings of the lance is therebylengthened. This is important, in particular, when sometimes large scrapfragments are in use and the preheating time during blasting with oxygenfrom nozzle4 and fuel from nozzle3 is kept short. Then, in particular,the oxygen jet from nozzle5 or else nozzle2 can be deflected and for ashort time a part quantity can brush the panel, as may also occur inconventional burners. Installing the multi-functional lance below acopper panel bulged in a wedge-shaped manner in the direction of thefurnace interior has proved particularly advantageous, since the lanceis thereby protected particularly well.

Operation with the multi-functional lance according to the invention maybe described as follows:

In the stand-by position, the nozzles are loaded with the media, air(nozzle1), air (nozzle2), N₂ (nozzle3), air (nozzle4) and air (nozzle5)in minimal quantities which, for example, flow at 0.2 bar.

During charging, the pressure at the nozzles is increased briefly toabout 1.5 bar when the lance is exposed to splashes from the furnacespace during charging.

After the charging of iron carriers, such as scrap and/or cast iron, andof lump coal, directly reduced iron, slag formers, etc., themulti-functional lance is activated in steps, starting from thekeeping-clear quantities (an admission pressure of below 1 bar) and isused for the various purposes. However, the time flow of the methodsteps also depends, inter alia, on the lumpiness of the feed substances,the planned profile of the carbon content of the melt, the metal oxidecontents in the slag, the necessary dephosphorization of the melt, etc.and may vary. In the extreme instance, all the functions are switched onfrom the outset and the lance is operated constantly for a period oftime.

In the case of average feed substances—conventional scrap—, typicaloperation is as follows:

First, after the ignition of the arc and flaming in the waste-gas elbow,oxygen through nozzle4 is switched on and, immediately thereafter, thefuel, such as, for example, natural gas (0.6 to 7 Nm³/min), from nozzle3 is connected. The scrap is preheated upstream of the lance (burnerfunction).

After a short time, which depends on the scrap mix used, for exampleafter two minutes, a mean oxygen throughflow from nozzle2 for thecutting and oxidizing melting of the scrap is switched on. Depending onthe precalculated O₂ quantity for refining, after a metal sump having adepth of, for example, 20 cm has been formed, the melt is decarbonizedwith a larger quantity of oxygen by means of an oxygen-jet pulsecontrolled by the first tube. In this case, the burner function remainsswitched on in most instances of use, in order to optimize theeffectiveness of melting and decarbonization and of the partialoxidization of the melt.

After the oxygen from nozzle5 has been connected, the burnable furnacegases are sucked into the individual oxygen jets and partially burnt.The energy released at the same time is transmitted with high efficiencyto the scrap, slag and melt and is not lost to the waste-gas system. Thelatter is even relieved of thermal load. The oxygen jets from nozzle5,that is to say 2 to 16 jets per multi-functional lance, blow askew awayfrom the longitudinal axis of the lance downwards into the scrap runninggear.

In a lance for low solid blow-in rates, the central nozzle1 can, if aspecial change-over valve is installed at the entrance to the nozzle, bechanged over from air to the oxygen mode and, after being scavenged withnitrogen, to, for example, the blowing-in of coal. When there is a highdemand for oxygen for refining purposes, coal injection is switched off,nozzle1 is scavenged with N₂ with the aid of the change-over valve, andnozzle1 and nozzle2 are loaded with a predetermined oxygen throughflow.

The oxygen quantity through nozzle2 is 400 to 3000 Nm³ per hour,depending on the furnace size and the number of multi-functional lances.Up to 0.3 kg/min of coal are blown through the nozzles6 per mm² ofblowing cross section. Depending on the operating mode, therefore, themelt can either be quickly refined or even carbonized. Through a nozzle6with a nominal width of 12 mm, it is possible, for example, to blow upto 34 kg/min of coal when low O₂ quantities are blown through nozzle2.By coal blasting, the slag is foamed very quickly and intensively, theFeO contents in the slags are stabilized at a low level to below 20%,and, even in the case of carbon contents of the melt of, for example,0.04%, the oxygen contents in the steel are reduced from about 1000 toabout 600 ppm. This also leads, inter alia, to lower consumptions ofalloying agents and to a purer steel. These effects may be reinforced byscavenging the melt with accurately regulatable scavenging nozzles whichare loaded with nitrogen and/or argon plus CH₄.

When low carbon contents of the melt of, for example, 0.03% have to beset and the slag must also foam in the superheating period of the melt,the coal is blown onto the slag through nozzle6 only at very lowpressure and with a small quantity/min and is thereafter refined again.

When relatively large carbon quantities are to be briefly supplied tothe melt or, for conditioning, to the slag, inert gas, air or smalloxygen quantities are blown through nozzle2 and large coal quantitiesthrough nozzle6. The pressure at the entrance to nozzle6 rises with theblowing-in of coal (or else the blowing-in of solid) according to thefollowing rule of thumb: ${f = \sqrt{\frac{1.4 + B}{1.4}}};$

in this, f represents the factor for the pressure rise in the case of aconstant carrier-gas quantity and B represents the carrier-gas contentin kg/Nm³.

Particularly in the case of Cr-alloyed melts, the reduction in the COpartial pressure and, consequently, in Cr slagging in the case of carboncontents of, for example, below 1% due to the admixture of inert gas orsteam to the oxygen from nozzle1, nozzle2 and nozzle4 is particularlyadvantageous.

As a result, carbon contents to below 0.4% can be produced efficiently,that is to say with a low degree of slagging of the alloying elements,at low temperature and with high productivity. Subsequent VOD treatment(Vacuum Oxygen Degassing) is thereby shortened appreciably and theentire productivity of the method route EAF, with a multi-functionallance or multi-functional lances and VOD, is increased substantially.Bottom blowing by means of oxygen and inert gas or steam, in combinationwith the multi-functional lances, is a particularly suitable combinationfor making alloyed steel, such as, for example, stainless steel, in theEAF, using the present method. In an extreme instance, stainless steelcan be made in such an EAF, even without VOD treatment.

The multi-functional lances according to the invention and their use areexplained in more detail hereafter in FIG. 1 to FIG. 9 of the drawings.

In this case, FIG. 1 to FIG. 3 of the drawings illustrate themulti-functional lance for blowing in relatively small solid quantities:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a reduced longitudinal section which is drawn throughthe central longitudinal axis of the multi-functional lance,

FIG. 2 shows the head of the multi-functional lance,

FIG. 3 is a view of the head illustrated in FIG. 2, in the direction ofthe arrow I of FIG. 2.

FIGS. 4, 5, 6 and 7 of the drawings illustrate the multi-functionallance according to the invention for blowing in relatively large solidquantities.

FIG. 4 illustrates a reduced longitudinal section through the entiredesign of this lance, whilst

FIG. 5 illustrates the head of the multi-functional lance.

A view of the head illustrated in FIG. 5, in the direction of the arrowIV, can be seen in FIG. 6.

FIG. 7 illustrates the multi-functional lance for relatively largequantities, together with the gas supply lines,

FIGS. 8 and 8a and FIGS. 9 and 9a show the installation ofmulti-functional lances according to the invention into metallurgicalvessels.

The multi-functional lance illustrated in FIG. 1 has a first tube 1which is used, in particular, for the supply of solid, fine-grained todust-like substances which can be conveyed pneumatically. This firsttube 1 extends in the direction of the central longitudinal axis 2 ofthe multi-functional lance and is surrounded by a second tube 3, bymeans of which a first annular gap 4, through which, in particular,oxygen-containing gas is supplied, is formed between the first andsecond tubes.

The inside of the second tube 3 is designed in the manner of a Lavalnozzle at the mouth end which is formed by a specific mouth part 5,easily releasable from the second tube 3 by means of a screw connection,so that the oxygen-containing gas or the oxygen emerges from the mouthpart 5 at supersonic velocity.

The second tube 3 is surrounded by a third tube 6, so as to form,between the second and third tubes, a second annular gap 7, throughwhich gaseous and/or liquid fuel is supplied.

A fourth tube 8 surrounds the third tube 6, so as to form, between thethird and fourth tubes, a third annular gap 9, through which, onceagain, in particular, oxygen-containing gas is supplied.

Furthermore, the fourth tube 8 is surrounded by a fifth tube 10, so asto form, between the fourth and fifth tubes, a fourth annular gap 11,through which, in particular, oxygen-containing gas is supplied.

The fourth annular gap 11 terminates, on the mouth side, in a pluralityof outflow ducts 12. The centre axes 13 of the outflow ducts 12 are skewto the longitudinal axis 2 of the multi-functional lance. The normalprojection of the centre axis 13 of each outflow duct 12 onto a planedrawn through the central longitudinal axis 2 and through the mouth ofthe outflow duct 12 (the said plane being identical to the drawing planein FIG. 2 of the drawing) forms with the central longitudinal axis 2 anangle α of 2.5 to 25°. As a measure of the skewness, the normalprojection of the centre axis 13 of each outflow duct 12 onto a planedirected normally to the central longitudinal axis 2 (this plane beingidentical to the drawing plane in FIG. 3 and this normal projectioncoinciding with the centre axis in the selected view of FIG. 3) forms,with a plane drawn through the longitudinal axis 2 and the mouth of theoutflow duct, an angle β of 2.5 to 60°.

As a result, the oxygen-containing gas blown in through the outflowducts 12 and, consequently, also the waste gases from the metallurgicalvessel, which are sucked into these oxygen gas jets, are set in ahelical mixing movement and the waste gases are sucked into the oxygengas jets. This leads to efficient intermixing of the oxygen-containinggas and waste gases and to the comprehensive post-combustion of these.

The fifth tube 10 is surrounded on the outside by a water-cooled doublecasing 14 which conventionally terminates in the same mouth plane 15 asthe first, second and third tubes 1, 3, 6 or their mouth parts. Thefourth tube 8 and fifth tube 10 may terminate, jointly with thewater-cooled double casing 14, in a second mouth plane 16, the firstmouth plane being set back (as illustrated by a broken line at 17)behind the second.

The mouth parts 5, 18 of the second 3 and third 6 tube are provided witha plurality of slots 19 on their outside, thereby achieving anintensified cooling effect on the gases supplied through the second 7and third 9 annular gap.

The first tube 1 is designed to be wear-resistant on the inside. Forthis purpose, it has a ceramic insert on the inside. The first tube 1can also be moved along the central longitudinal axis, as indicated bythe arrow II, for example by means of a pneumatic drive.

Both the third 6 and the fourth 8 tube are divided in their length andthe respective tube parts 6 a, 6 b and 8 a, 8 b are fastened to oneanother by means of screw connections. As a result, the tube parts 6 band 8 b can be quickly exchanged in the event of a repair. Sealing-offtakes place, for example, by means of an O-ring.

The multi-functional lance illustrated in FIG. 4 has a first tube 20which is used, in particular, for the supply of oxygen-containing gas.This first tube 20 extends in the direction of the central longitudinalaxis 21 of the multi-functional lance and is surrounded by a second tube22, by means of which a first annular gap 23, through which, once again,in particular, oxygen-containing gas is supplied, is formed between thefirst and second tubes.

When oxygen-containing gas is supplied through the first tube 20, thelatter serves mainly for controlling the pulse of the gas jet out of thefirst annular gap 23 or for controlling the FeO contents of slags. Forthis purpose, the first tube 20 can be moved along the centrallongitudinal axis 21, as indicated by the arrow III, for example bymeans of a pneumatic drive. However, a liquid blow-in step can also becarried out by means of the first tube 20.

The inside of the second tube 22 is designed in the manner of a Lavalnozzle at the mouth part 24, so that the oxygen-containing gas or theoxygen emerges from the mouth part 24 at supersonic velocity.

The second tube 22 is surrounded by a third tube 25, so as to form,between the second and third tubes, a second annular gap 26, throughwhich gaseous and/or liquid fuel is supplied.

A fourth tube 27 surrounds the third tube 25, so as to form, between thethird and fourth tubes, a third annular gap 28, through which, onceagain, in particular, oxygen-containing gas is supplied.

Furthermore, the fourth tube 27 is surrounded by a fifth tube 29, so asto form, between the fourth and fifth tubes, a fourth annular gap 30,through which cooling water is supplied.

Furthermore, the fifth tube 29 is surrounded by a sixth tube 31, so asto form, between the fifth and sixth tubes, a fifth annular gap 32,through which, in particular, oxygen-containing gas is supplied.

The fifth annular gap 32 terminates, on the mouth side, in a pluralityof outflow ducts 33. The centre axes 34 of the outflow ducts 33 are skewto the longitudinal axis 21 of the multi-functional lance. The normalprojection of the centre axis 34 of each outflow duct 33 onto a planedrawn through the central longitudinal axis 21 and through the mouth ofthe outflow duct 33 (the said plane being identical to the drawing planein FIG. 5 of the drawing) forms with the central longitudinal axis 21 anangle α of 2.5 to 25°. As a measure of the skewness, the normalprojection of the centre axis 34 of each outflow duct 33 onto a planedirected normally to the central longitudinal axis 21 (this plane beingidentical to the drawing plane in FIG. 6 and this normal projectioncoinciding with the centre axis in the selected view of FIG. 6) forms,with a plane drawn through the longitudinal axis 21 and the mouth of theoutflow duct, an angle β of 2.5 to 60°.

As a result, the oxygen-containing gas blown in through the outflowducts 33 and, consequently, also the waste gases from the metallurgicalvessel, which are sucked into these oxygen gas jets, are set in ahelical mixing movement and the waste gases are sucked into the oxygengas jets. This leads to efficient intermixing of the oxygen-containinggas and waste gases and to the comprehensive post-combustion of these.

The sixth tube 31 is surrounded on the outside by a seventh tube 35,thereby forming a sixth annular gap 36, through which cooling water isdrawn off.

The fourth 30 and sixth 36 annular gap are designed to be closed on themouth side and are connected by means of bores 38 in the head 37 of themulti-functional lance. The fourth 30 and sixth 36 annular gap form,together with the bores 38, a water-cooled double casing, through whichapproximately 60 m³/hour of water flow during operation.

A plurality of nozzle tubes 39 for the supply of dust-like tofine-grained solids run within the fifth annular gap 32, only one of thenozzle tubes 39 being illustrated in cross section in FIG. 4 and FIG. 5of the drawings on account of the selected view. The nozzle tubes 39 aredesigned to be wear-resistant on the inside, for which purpose they areprovided with a ceramic insert. The nozzle tubes 39 open out in the head37 of the multi-functional lance or pierce the said head. The mouths ofthe nozzle tubes 39 are cylindrical here, but may also be widenedslightly conically or be designed in the form of a Laval nozzle.

In special cases, when the use of the outflow ducts 33 forpost-combustion is dispensed with, the entire fifth annular gap 32 mayadditionally be loaded with carrier gas and solid. The solid is thenblown through the outflow ducts 33 which are designed to bewear-resistant in this case.

The mouth parts 24, 40 of the second 22 and third 25 tube are providedwith a plurality of slots 41 on their outside, as a result of which anintensified cooling effect on the gases supplied through the second 26and third 28 annular gap is achieved.

The mouth parts of the fourth 27, fifth 29, sixth 31 and seventh 35 tubeterminate in a first mouth plane 42. The mouth parts 24, 40 of thesecond 22 and third 25 tube terminate in a second mouth plane 43, thesecond mouth plane being set back somewhat behind the first.

Both the fourth 27 and the fifth 29 tube are divided in their length,the fourth tube 27 twice and the fifth tube 29 once, and the respectivetube parts are fastened to one another by means of screw connections 44.As a result, the respective tube parts can quickly be exchanged in theevent of a repair. Sealing-off takes place, for example, by means ofO-rings.

The water-cooled parts of the head 37 of the multi-functional lance,that is to say the mouth parts of the fourth to seventh tube 27, 29, 31,35, are preferably made from copper, specifically either welded orforged, but preferably cast. After only one weld seam has been severedin each case, these parts can easily be drawn off and thereforereplaced.

The nozzle tubes 39 are assigned, approximately in the middle of themulti-functional lance, a solid-distribution chamber 45 which isdesigned as an annular hollow body and which surrounds themulti-functional lance. Located within the solid-distribution chamber 45is a further annular hollow body 46 which, however, is designed to beopen at the top, with the result that a gap remains between the cover 47of the solid-distribution chamber 45 and the lateral limitation 48 ofthe further annular hollow body 46. The nozzle tubes 39 pierce thebottom 49 of the solid-distribution chamber 45 and open into the bottom50 of the further hollow body 46. A solid supply 51 opens into thesolid-distribution chamber 55 approximately tangentially to the latter.Blown-in solids are distributed in the solid-distribution chamber 45 andflow via the lateral limitation 48 of the further hollow body 46, thesaid limitation forming a kind of overflow, first into the furtherhollow body 46 and then into the nozzle tubes 39.

FIG. 7 of the drawing illustrates the gas and solid supply system of amulti-functional lance (for relatively large solid quantities).

A fuel supply 52, a carrier-gas supply 53, an oxygen supply 54, an airsupply 55, one or more solid supplies 56 and, for special instances ofuse, a steam supply 57 are provided for supplying all the gases andsolids necessary for all the instances of use.

Hydrocarbons, such as methane, ethane, propane or butane, CO or mixturesof these gases, are mostly used as fuel, but, depending on availability,it may also be appropriate to use liquid fuels, for example fuel oil, inwhich case it is advantageous, particularly in the case ofhigh-viscosity oils, if the respective fuel is preheated before it isused.

Inert gases, such as nitrogen, argon or mixtures of these gases, aretypically used as carrier gas. Depending on the instance of use,however, other gases, for example air or natural gas, may also beemployed as carrier gas.

The first tube 20 and the first 23, second 26, third 28 and fifth 32annular gap are provided with gas feed lines 58, 59, 60, 61, 62, thesecond annular gap 26 being connected to the fuel supply 52 and thecarrier-gas supply 53, and the remaining annular gaps 23, 28, 32 as wellas the first tube 20 being in each case connected both to thecarrier-gas 53, oxygen 54 and air 55 supply and, for special instancesof use, to the steam supply 57.

For the coal and solid blow-in functions of the multi-functional lanceaccording to the invention, the carrier-gas feedline 63 to thesolid-distribution chamber 45 and, for special cases, the gas feedlines59, 61, 62 to the first, third and fifth annular gap are in each caseprovided with solid supplies 56 which can in each case be connected anddisconnected to the effect of comprehensive functional versatility.

The main quantity of solids, here, once again, mainly coal, is blown viathe nozzle tubes 39. However, in exceptional cases, further quantitiesof solids may also be blown at any time via one or more of the annulargaps 23, 28 and 32, in which case the respective carrier gas for solidblowing may be oxygen, air, steam or mixtures of these gases.

Furthermore, the multi-functional lance, or the fourth 30 and the sixth36 annular gap, are equipped with a cooling-water inflow 64 and acooling-water outflow 65. Water cooling itself may be dispensed with inmany instances of use. Thus, in certain cases, this is also possible inthe electric furnace, if there is no obligation to maintain theoutstanding durability of the lance head.

FIG. 8 shows a vertical section through an electric furnace 66, in whichmulti-functional lances 67, 68 according to the invention are arranged.Furthermore, the penetration of the jets 69 into the melt 70 or the slag71, and the oxygen jets (short arrows 72) for the post-combustion of thefurnace waste gases, are illustrated. Moreover, conventionalburner/post-combustion lances 75, as well as a door burner 74 and bottomscavenging nozzles 75, are arranged in the electric furnace 66, and atapping point 76 is provided. The multi-functional lances 68 areprotected by a panel 77 curved forwards towards the furnace interior.

FIG. 8a illustrates a horizontal section through the electric furnace 66from FIG. 8. The multi-functional lances 68 are arranged approximatelytangentially to a circle which is concentric to the electrode referencecircle 78. This prevents excessive electrode consumption or prematurewear. The further multi-functional lance 67 is arranged in the bay 79 ofthe electric furnace 66.

FIG. 9 and FIG. 9a illustrate the arrangement of the multi-functionallances 67, 68 in an electric furnace 80 with an excentric shaft, theburner/post-combustion lances 73 and bottom nozzles 75. A furthermulti-functional lance 81 is introduced by means of a lifting gear (notillustrated in the drawing), which stands outside the electric furnace80, into one or more positions through orifices in the roof into thefurnace interior for blasting purposes. In this type of furnace, it isparticularly important for the preheated and partly already pasty scrap82 to move in the direction of the electrodes 86 without the formationof skull.

This is achieved in a particularly impressive way by means of the nozzlearrangement illustrated. It was possible to lower the tapping times tobelow 40 minutes and the current consumption to below 290 kWh/t ofliquid steel. The multi-functional lance introduced through the furnaceroof also contributed to this.

PRACTICAL EXAMPLES

The designations, nozzle1, nozzle2, nozzle3, nozzle4, nozzle5 andnozzle6 for the first tube, the first, second, third and fifth annulargaps and the nozzle tubes or their respective mouth parts are used againin the following examples.

Example 1

In a 115-t electric furnace with a transformer power of 80 MVA, 3multi-functional lances (49 and 50), as illustrated in FIGS. 5 and 5a,were installed. The furnace was also equipped with 2 bottom scavengingnozzles and 4 post-combustion/burner lances 55 as well as a door burner57.

After the charging of the first scrap basket with 49 t of scrap, 19 t ofsolid pig iron and 1000 kg of lumpy coal onto a metal sump ofapproximately 20 t, nozzle1, nozzle2, nozzle4 and nozzles being operatedwith air during charging, nozzle3 and nozzle4 were loaded with 6 Nm³ ofO₂/min (nozzle4) and 3 Nm³ of CH₄/min (nozzle3) . After 2 minutes,nozzle2 and nozzle5 were changed over from air to oxygen and loaded with6 (nozzle2) and 4.5 Nm³/min respectively. Air, in each case with 5kg/min of fine-grained coal, was blown through nozzle6, in order toaccelerate the melting of the scrap and control scrap oxidation. 5minutes after power-on, that is to say after an increase in the quantityof melted metal, the oxygen quantity of nozzle2 was increased to 16Nm³/min and the conveyance of coal through nozzle1 doubled to 12 kg/min.Towards the end of the melting-down operation for the first basket, theoxygen quantity through nozzle5 was decreased again.

57 t of scrap were charged in the second basket, and, by means of themulti-functional and post-combustion lances, the same procedure, such asthe preheating, cutting, accelerated melting and post-combustion of thefurnace waste gases, was carried out, and intensive refining was carriedout by means of the oxygen jets of nozzles5 from the 3 multi-functionallances. The two bottom nozzles 57 were operated respectively at 0.4 Nm³of N₂/min and 0.2 Nm³ of CH₄/min, which were premixed in thegas-regulating station, although only at half the rates during the twoflat bath periods. The oxygen quantities through all the post-combustionlances 55 were adapted to the waste-gas analysis, so that the CO contentdid not rise above about 10% in the waste gas.

The blowing-in of coal was set, inter alia, according to the requirementfor the formation of foamed slag and for a carbon content in the melt ofapproximately 1580° C. and approximately 0.30% respectively. During aperiod of 3 minutes, the coal was replaced by a granulated shredderlightfraction. The foaming of the slag also functioned by this means. In thesuperheating period, refining was carried out with up to altogether 4500Nm³ of O₂/hour. Meanwhile, the post-combustion nozzles (nozzles5) of themulti-functional lances 49 and 50 and the burner 55 were kept clear byair. 2 minutes before tapping and after slagging-off, coal was blownintensively, once again, with a minimal refining effect, in order tolower the oxygen content of the melt to about 600 ppm.

At 0.3% C. in the melt (melt-down), the FeO content in the slag was 18%and the yield of liquid steel was therefore also high at 92%. Thetapping follow-up time and the melting capacity were around 52 min. andabove 132 t/h respectively. Consumptions amounted to 39 kg of lime/t,2.1 kg of electrodes/t, 9 kg of lumpy coal/t, 12 kg of blow-in coal/t,55 Nm³ of O₂/t, 4 Nm³ of CH₄/t and 290 kWh/t of liquid steel. Themulti-functional lances used in this case had a durability of 800batches. Only the nozzles for blowing in the coal were exchanged once asa precaution.

Example 2

In the production of a melt alloyed with chromium in a 60-t electricfurnace, it was possible to lower the carbon content of the melt from0.8 to 0.3% with the aid of 3 smaller multi-functional lances. The Cr₂O₃content of the slag could be kept below 12% by blasting with 40% O₂ and60% N₂ in the last third of the refining period. In these tests, 3scavenging nozzles, which were operated with N₂+CH₄, were used in thebottom of the electric furnace. By means of this refining period withthe multi-functional lances, subsequent VOD treatment could be shortenedby 30 min/batch. The slag was foamed by blowing in slag formers. Forthis purpose, however, the blown-in solid quantity had to be increasedto altogether 90 kg/min. The final carbon content was 0.03%.

Example 3

In the melting-down of 80% DRI and 20% scrap, one multi-functional lancewas mounted in the tapping region of the furnace bay and 2multi-functional lances were mounted so as to be capable of being movedthrough the roof of the furnace into the furnace interior. These twolances blew in the direction of the point of impingement of the DRI'sconveyed continuously into the furnace. This bath region was alsointermixed more effectively by means of 2 scavenging nozzles which wereinstalled into the bottom of the furnace and which blew with N₂+CH₄. Themain advantage was a reduction in the tapping time in this 150-telectric furnace from 105 to 83 minutes. Productivity was increased by20%.

Example 4

In a 65-t converter bottom-blowing with oxygen and lime dust, amulti-functional lance was arranged in a stationary manner outside theradius of the converter. 200 Nm³ of O₂/min were blown on through thebottom and up to 105 Nm³ of O₂/min blown on by the multi-functionallance in the main decarbonization period. By means of the 3-minute scrappreheating, the blowing-on of 15 kg of coal/t and the partialpost-combustion of the converter waste gases in the converter and heattransmission, it was possible for the scrap rate (in relation to theyield of liquid steel) to be increased from 22 to 27%. It was possibleto reduce the number of bottom nozzles, enlarge the distance between thenozzles and increase the durability of the bottom from 700 to 820batches. It was also particularly important that the metal and slagcrusts inside the upper converter cone were reduced to such an extentthat they no longer had to be removed by being burnt off or by beingbroken out in a time-consuming way. The converter availability wasthereby increased. Due to the particular feature of the multi-functionallance, the oxygen supply could be shifted from the side nozzle in theconverter wall to outside the radius of the converter. The runninglength of the free jet was increased by 2.4 m, without any adverseeffect.

Example 5

It proved particularly advantageous to use the multi-functional lancesin a 120-t DC electric furnace, in which the metallic feed stockconsisted of 52% liquid pig iron low in trace elements and 48% scrap.However, the pig iron had a phosphorus content of 0.15%. In thiselectric furnace with a transformer power of 95 MVA, 4 multi-functionallances were installed into the side wall of the furnace. 2 of the 4lances did not carry out any blowing-in of coal, since liquid pig ironcontains sufficient carbon. However, nozzles6 were periodically loadedwith lime dust (altogether 100 kg/min), in order to assist phosphorusslagging. This also included the measure of loading nozzles1 of themulti-functional lances with high oxygen pressure (8 bar) in someblasting periods, with the result that the FeO content of the slagincreased from 20 to 35%. The result of this was that it was possible toraise the distribution of the phosphorus between the slag and melt from50 to 90, that is to say dephosphorization was appreciably improved,with the result that a phosphorus content of 0.015% could be set in thefinished sample without any loss of time. The slag quantity was 120 kg/tof liquid steel.

The two water-cooled oxygen lances present, which are normally movedinto the furnace through the slag door for refining and slag foaming,were removed. The furnace door was opened only for slagging-off, withthe result that the entry of cold nitrogen-containing air wassubstantially reduced. The following operating mode was adopted:

After the charging of the first and only scrap basket, the scrap regionbelow the electrode was melted in 5 minutes, the furnace roof was openedand the liquid pig iron was quickly emptied into this space by means ofthe pig-iron ladle. Until this interruption in the current supply, themulti-functional lances were operated in the burner mode and, before thepig iron was emptied in, in the post-combustion and scrap-cutting modes.After the pig iron had been emptied in, refining was carried out, ineach case with 1700 Nm³ of O₂/h, at the 4 points where the refining jetsof the multi-functional lances impinged onto the melt. Nozzles5 for thepost-combustion of the furnace gases blew at a shorter distance awayfrom the longitudinal axis of the multi-functional lance than in furnaceoperation with 100% scrap feed. The heat released during post-combustionwas thereby transmitted with higher efficiency to the slag and melt.

The result was a lowering of current consumption from 225 to 190 kWh/tof liquid steel, a shortening of the tapping follow-up time by 10% and alowering of the nitrogen contents in the finished steel from 58 to 49ppm on average. In this use, too, the durability of the multi-functionallances is much higher than that of the water-cooled refining lances.

The invention is not restricted to the exemplary embodiments illustratedin the drawings and the examples, but also embraces all the means, knownto the average person skilled in the art, which may be employed forimplementing the invention.

Thus, it is within the scope of the invention to combine the variouspossibilities, which allow the multi-functional lances and theiroperating modes, in different embodiments and also to adapt thesepossibilities to the operating conditions of other reactors for theproduction of a wide variety of melts, for example of ferro-alloys withlow carbon contents.

What is claimed is:
 1. A method for producing a metal melt in ametallurgical vessel, wherein feed substances which contain metalsand/or metal oxides are charged in solid and/or molten form into themetallurgical vessel, the main part of the energy necessary for themelting and/or the finish-reduction of the feed substances is appliedelectrically and/or by the combustion and/or the gasification ofcarbon-containing materials, comprising the steps of: A) supplyingadditional energy to the feed substances by the blowing-in, by means ofone or more multi-functional lances, and the combustion of gaseousand/or liquid carbon-containing materials and oxygen-containing gas; B)cutting and partially melting the solid feed substances by theintensified blowing-in of oxygen-containing gas by means of themulti-functional lance; C) refining the melted feed substances by theintensified blowing-in of oxygen-containing gas by means of themulti-functional lance; D) alloying carbon and/or supplying additionalenergy to the feed substances by the blowing-in and/or burning offine-grained and/or dust or powder-type solid carbon-containingmaterials by means of the multi-functional lance; E) after-burning, in apost-combustion step, waste gases from the metallurgical vessel by theblowing-in of oxygen-containing gas into the waste-gas space of themetallurgical vessel by means of the multi-functional lance, wherein thejet of the oxygen-containing gas from each multi-functional lance isskewed to the central longitudinal axis of the respectivemulti-functional lance and is set in a helical rotational movement; F)supplying necessary substances to the feed substances by the blowing-inof fine-grained, dust, and/or powder-type solid aggregates and/oralloying agents by means of the multi-functional lance, in order toachieve a desired composition of the metal melt; wherein a performanceof each step A) through F) depends on the composition of the feedsubstances and on the desired composition of the metal melt, selectivelyin any desired combination, in succession and/or in reverse order and/orsimultaneously and/or omitting the step D) and/or the step F).
 2. Themethod of claim 1, wherein an electric furnace or a steel converter or amelting-down gasifier or a ladle or a vessel for the conversion of slagis used as a metallurgical vessel.
 3. The method of claim 1, wherein oneor more multi-functional lances are used jointly with burners, refininglances, post-combustion lances, under-bath nozzles, hollow electrodes,and/or side nozzles.
 4. The method of claim 1, wherein one or more ofthe following substances are blown into or onto the partially orcompletely melted feed substances: metal ores, metal oxides, nickeloxide, vanadium oxide and chrome oxide, iron carbide, calcium carbide,aluminium, FeSi, FeCr, FeMn, oil-containing scale, slags, slag formers,dusts from dedusting systems, grinding dusts, metal chips, deoxidants,shredderlight fraction, lime, coal, coke and sponge iron, in each casein fine-grained, dust, and/or powder-type form.
 5. The method of claim1, wherein the blowing-in of oxygen-containing gas of step E) takesplace in a periodically fluctuating and/or pulsating manner.
 6. Themethod of claim 1, wherein step D) and/or step F) further comprising, inan electric furnace, the jet from a multi-functional lance is directedinto the vicinity of a point of impingement or into the point ofimpingement of solid material, which is charged onto the melt via anorifice in the furnace roof, or of an arc on the melt.
 7. The method ofclaim 1, wherein step D) or step F) further comprising, in a converter,the jet from a multi-functional lance is directed into the vicinity of apoint of impingement or into the point of impingement of an oxygen jetfrom a further lance or a side nozzle on the melt.
 8. The method ofclaim 1, wherein one or more of the steps A), B), D), E), and/or F) aresimultaneously performed with a refining step by means of amulti-functional lance.
 9. The method of claim 8, wherein a combustionstep is simultaneously performed with a refining step by means of amulti-functional lance.
 10. The method of claim 1, wherein in a refiningstep during the production of alloyed iron melts with a low carboncontent, steam and/or an inert gas, and/or rare gases are blown into oronto the partially or completely melted feed substances, in addition tothe intensified blowing-in of oxygen-containing gas.
 11. The method ofclaim 1, wherein in a carbon blow-in step, during the production of ironmelts or steel melts with a low carbon content, the carbon-containingmaterials are blown at low velocity only onto and into the slag locatedabove the melt.
 12. The method of claim 1, wherein during one or more ofthe steps A), B), C), or E), the following step is performed: G)blowing-in and thermally decomposing burnable and/or unburnable liquidsby means of the multi-functional lance.
 13. The method of claim 12,wherein step G) is performed during a refining step, or the liquid jetis directed onto a point of impingement of an arc on the melt.
 14. Themethod of claim 1, wherein during the refining step C), the blown-in jetof the oxygen-containing gas is influenced in a controlled manner by theblowing-in of a further gas jet.
 15. A multi-functional lance for use ina method for producing a metal melt in a metallurgical vessel,comprising: a plurality of tubes which surround one another and areconcentric to a central longitudinal axis and a common end of whichforms the head of the multi-functional lance; a first tube for forming asupply duct for solid, fine-grained, dust, and/or powder-typesubstances; a second tube surrounding the first tube so as to form afirst annular gap for the supply of an oxygen-containing gas, whereinthe mouth part of the second tube being designed as a Laval nozzle; athird tube surrounding the second tube so as to form a second annulargap for the supply of gaseous and/or liquid fuel; a fourth tubesurrounding the third tube so as to form a third annular gap for thesupply of an oxygen-containing gas; a fifth tube surrounding the fourthtube so as to form a fourth annular gap for the supply of anoxygen-containing gas, wherein the fourth annular gap terminates on themouth side, so as to form a plurality of outflow ducts, wherein thecentre axis of each outflow duct is skew to the central longitudinalaxis so that the oxygen-containing gas is set in a helical rotationalmovement.
 16. The multi-functional lance of claim 15, wherein theoutside of the fifth tube is provided with a water-cooled casing. 17.The multi-functional lance of claim 15, wherein the mouth parts of thefirst tube, the second tube, and the third tube each terminate in afirst mouth plane that is normal to the central longitudinal axis andthe mouth parts of the fourth tube and the fifth tube each terminate ina second mouth plane that is normal to the central longitudinal axis,wherein the first mouth plane is set back behind the second.
 18. Themulti-functional lance of claim 17, wherein the first tube and/or thesecond tube is manufactured from either an alloyed steel with chromiumcarbides, a hard-chrome-plated steel, a hard-chrome-plated copper,copper, or a steel which is provided with a ceramic insert or coveringon the inside and/or on the outside of the tube.
 19. Themulti-functional lance of claim 15, wherein the third tube and thefourth tube are divided by length and the respective tube parts arefastened to one another by means of releasable connections.
 20. Themulti-functional lance of claim 15, wherein the mouth of the first tube,the third tube, the fourth tube, and/or the outflow ducts is a Lavalnozzle.
 21. The multi-functional lance of claim 15, wherein the firsttube, the first annular gap, the second annular gap, the third annulargap, and the fourth annular gap are connected to a carrier-gas supply.22. The multi-functional lance of claim 15, wherein the first tube, thefirst annular gap, the third annular gap, and the fourth annular gap areeach connected to an oxygen supply, an air supply, and/or a steamsupply, wherein the solid injections of each are connectable anddisconnectable.
 23. The multi-functional lance of claim 15, wherein achange-over can be made from the carrier-gas supply and solid supply ofthe first tube to the supply of oxygen by means of a change-over device.24. A multi-functional lance for use in a method for producing a metalmelt in a metallurgical vessel comprising: a plurality of tubes whichsurround one another and are concentric to a central longitudinal axisand a common end of which forms the head of the multi-functional lance;a first tube for forming a supply duct for liquids or oxygen-containinggas; a second tube surrounding the first tube so as to form a firstannular gap for the supply of an oxygen-containing gas, wherein themouth part of the second tube is a Laval nozzle; a third tubesurrounding the second tube so as to form a second annular gap for thesupply of gaseous and/or liquid fuel; a fourth tube surrounding thethird tube so as to form a third annular gap for the supply of anoxygen-containing gas; a fifth tube surrounding the fourth tube so as toform a fourth annular gap for the supply of cooling water, wherein thefourth annular gap is closed on the mouth side; a sixth tube surroundingthe fifth tube so as to form a fifth annular gap for the supply ofoxygen-containing gas, wherein the fifth annular gap terminates on themouth side, so as to form a plurality of outflow ducts, and the centreaxis of each outflow duct is skew to the central longitudinal axis, sothat the oxygen-containing gas is set in a helical rotational movement;a seventh tube surrounding the sixth tube so as to form a sixth annulargap for drawing off cooling water, wherein the sixth annular gap isclosed on the mouth side, and the fourth annular gap is connected to thesixth annular gap, in the region of the head of the multi-functionallance, by means of bores which do not cross the outflow ducts; one tonine nozzle tubes of wear-resistant design for the supply of solid,fine-grained, dust, and/or powder-type substances, wherein the nozzletubes arranged within the fifth annular gap and the centre axis of eachnozzle tube are parallel to the longitudinal axis, and the nozzle tubespierce the head of the multi-functional lance, without crossing bores oroutflow ducts.
 25. The multi-functional lance of claim 24, wherein themouth parts of the second tube and of the third tube terminate in afirst mouth plane that is normal to the central longitudinal axis andthe mouth parts of the fourth tube, the fifth tube, the sixth tube, andthe seventh tube terminate in a second mouth plane that is normal to thecentral longitudinal axis, wherein the first mouth plane is set backbehind the second.
 26. The multi-functional lance of claim 24, whereinat least one of the third tube, the fourth tube, the fifth tube, thesixth tube, and/or and the seventh tube is divided at least once bylength, and the respective tube parts are fastened to one another byscrew connections and/or sliding connections that are sealed off bymeans of O-rings.
 27. The multi-functional lance of claim 24, whereinthe mouth of the third tube, the fourth tube, the outflow ducts, and/orthe one to nine nozzle tubes is a Laval nozzle and/or the mouth of thefirst tube is widened in diameter.
 28. The multi-functional lance ofclaim 24, wherein the one to nine nozzle tubes is manufactured fromeither an alloyed steel with chromium carbides, a hard-chrome-platedsteel, a hard-chrome-plated copper, or a steel which is provided with aceramic insert or covering on the inside and/or on the outside of thetube.
 29. The multi-functional lance of claim 24, wherein asolid-distribution chamber is assigned to the one to nine nozzle tubesat an end which faces away from the head of the multi-functional lance,wherein the solid-distribution chamber comprises a first annular,essentially cylindrical hollow body that is enclosed and has a bottom, acover, and a lateral limitation; the one to nine nozzle tubes pierce thebottom of the solid-distribution chamber from below; and at least onesolid supply tangentially opens into the lateral limitation of thesolid-distribution chamber.
 30. The multi-functional lance of claim 29,further comprising a second annular, essentially cylindrical hollowbody, wherein the hollow body is open at the top and has a bottom and alateral limitation, and is located within the solid-distribution chamberin such a way that a gap remains between the cover of thesolid-distribution chamber and the lateral limitation of the secondhollow body, and the one to nine nozzle tubes open into the bottom ofthe second hollow body.
 31. The multi-functional lance of claim 24,wherein the solid-distribution chamber is connected via a carrier-gasfeedline to a carrier-gas supply and to one or more solid supplies. 32.The multi-functional lance of claim 24, wherein the one to nine nozzletubes is connected to a carrier-gas supply and to a solid supply. 33.The multi-functional lance of claim 24, wherein the first tube, thefirst annular gap, the second annular gap, the third annular gap, andthe fifth annular gap are each connected to a carrier-gas supply. 34.The multi-functional lance of claim 24, wherein the first tube, thefirst annular gap, the third annular gap, and the fifth annular gap areeach connected to an oxygen supply, an air supply and/or a steam supply.35. The multi-functional lance of claim 15, wherein two to sixteenoutflow ducts are provided.
 36. The multi-functional lance of claim 15,wherein the normal projection of the centre axis of each outflow ductonto a plane drawn through the central longitudinal axis and through themouth of the outflow duct forms with the central longitudinal axis anangle α of 2.5° to 25°.
 37. The multi-functional lance of claim 15,wherein the normal projection of the centre axis of each outflow ductonto a plane directed normally to the central longitudinal axis forms,with a plane drawn through the central longitudinal axis and through themouth of the outflow duct, an angle β of 2.5° to 60°.
 38. Themulti-functional lance of claim 15, wherein the aperture angle γ of theconical part of the mouth of the second tube is 0.1° to 5°.
 39. Themulti-functional lance of claim 15, wherein the mouth parts of thesecond tube and/or third tube have slots on the outside of the tube andthese slots are arranged parallel to the central longitudinal axis. 40.The multi-functional lance of claim 15, wherein the first tube ismovable within the second tube along the central longitudinal axis. 41.The multi-functional lance of claim 15, wherein the mouth part of thesecond tube is releasably connected to the second tube.
 42. Themulti-functional lance of claim 15, wherein the second annular gap isconnected to a fuel supply for the supply of liquid and/or gaseous fuel.43. The multi-functional lance of claim 15, the supply of gases to themulti-functional lance is set by means of simple rigid diaphragms and/orquick-acting stop valves which are arranged in the individual gas lines.44. The multi-functional lance of claim 15, wherein electromagneticwaves in the range of visible light to infrared are emitted by a metalmelt and are detectable through the first tube and/or the first annulargap by means of an optical system and are fed to a detector fordetermining the temperature and/or chemical composition of the metalmelt.
 45. The multi-functional lance of claim 15, wherein themulti-functional lance is stationary, displaceable along itslongitudinal axis, and/or pivotable.
 46. The multi-functional lance ofclaim 15, wherein the multi-functional lance is arranged below a copperpanel bulged in the direction of the interior of the metallurgicalvessel.
 47. The multi-functional lance of claim 15, wherein one to tenmulti-functional lances are provided.